I've entered the fuel flow, speed, lease, turn time, seating data on every Western aircraft available in AirlineEmpires that carries over 50 passengers and was in production since 1970. I wrote a formula that assesses the potential value of each aircraft that can be summarized as the profit the aircraft would generate operating a route 80% of its range, divided by the cost of the aircraft.
A large plane with a rating of 800 will make far more than a smaller plane with a rating of 800. However, a fleet of smaller planes that cost equally as much to lease total as a single large plane will make the same amount.
The formula does not include maintenance, and because fuel cost varies wildly over time (and I chose an average), it is not fair to compare plane ratings from wildly different time periods.
The full repository of values (and a finder feature) can be downloaded from Google Sheets here: http://tinyurl.com/planerate. Here is an example of the Finder feature in use:
If you're unfamiliar with spreadsheets, etc, I made the following easier charts that show the best aircraft (by value) in each category.
^ Correction, Boeing 707-320B should be in the 150-250/5000+ slot.
^ Correction, Boeing 767-200ER should be in the 250-350/6500+ slot